Where and how do you find or get schematics?
How and where do you guys find schematics that you need to get a job done?
I have made a post here and one in the other schematic Usenet newsgroup for alt.binaries.schematics.electronic, plus a couple of web boards and have come up with nothing. So do you make a polite request in a Usenet newsgroup (Which one(s)? Or post a request on a web board or forum, if so which ones, or do you just give up and scrap the job or try to work without it. Many jobs can be done without them but someimes you really have to have the service manual or at the very least, the schematic diagram. Right now I am doing a "Carver Creation" with that Carver "magnetic field core" power supply; a Sunfire True Subwoofer Super Junior that has a blown amplifier in it. Both F1 & F2, 4A 250V fuses are open and the output transistors, Q7 2SC3181 & Q11 2SA1302 are shorted. I have cut these transistors from the board and they are indeed shorted. The MOSFETS; Q10, Q12, Q21, & Q24, IRF640, appear to be dead shorted between main terminals 2 & 3, the gate on terminal 1 averages about 160 ohms to the main terminals 2 &3. I have removed them from the board for further testing and found that two of them were indeed shorted. The good news is that I have tested with my Fluke meter some of the small SMD components near the output section and can find nothing burned, shorted, or open. Everything else looks good but for the two large output transistors, 2 of the TO220 MOSFETS, and 2 GMA 4 A fuses. I am afraid to try to fire this thing up when fixed because of that Carver "magnetic field core" power supply, I cannot variac it up slow and watch the current nor can I use a 100 watt light bulb in place of the main fuse. It seems to be a matter of replace the for sure bad ****, check all around, pray, keep fingers crossed, plug it in and watch for smoke. :( Any ideas on how to get the schematic, service manual, or tips on working on this small beast? I am between jobs so I cannot afford to just buy the service manual, even if it were indeed available. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
Where and how do you find or get schematics?
"Ohmster" How and where do you guys find schematics that you need to get a job done? ** You often have to use persistence and ingenuity to get them out of the makers. Looks like Carver / Sunfire are keeping theirs secret. I am afraid to try to fire this thing up when fixed because of that Carver "magnetic field core" power supply, I cannot variac it up slow and watch the current nor can I use a 100 watt light bulb in place of the main fuse. ** Sure you can. Just bridge out the T1 and T2 terminals on that triac in the AC supply. The PSU then reverts to entirely conventional - but will produce full DC rails with only 65% of nominal AC volts going in. Go any higher and the tranny's magnetic core will saturate and blow the AC fuse. Use a small fuse ( ie 1 or 2 amps) when playing about. It seems to be a matter of replace the for sure bad ****, check all around, pray, keep fingers crossed, plug it in and watch for smoke. :( ** Recipe for disaster. ....... Phil |
Where and how do you find or get schematics?
[posted and mailed]
"Phil Allison" wrote in : "Ohmster" How and where do you guys find schematics that you need to get a job done? ** You often have to use persistence and ingenuity to get them out of the makers. Looks like Carver / Sunfire are keeping theirs secret. Hmm, yeah it does. I wrote them for just a teeny weenie copy of the amp and PS circuit but no answer yet. I am afraid to try to fire this thing up when fixed because of that Carver "magnetic field core" power supply, I cannot variac it up slow and watch the current nor can I use a 100 watt light bulb in place of the main fuse. ** Sure you can. The dickens you say. I attached a small piece of the Carver M-400 PSU or you can see it he http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif Using this diagram, you are saying to just "short the triac" with wire, main terminal to main terminal, leave the gate alone. For sure this would make WAY to much power and blow the thing up but you say to bring it up slow with a variac and stay down around 50-65% of the AC line and monitor the "rails" on the amp to see if it is stable, not dumping DC, and does not draw excessive current? Hey that is brillient! Dam, I don't have a variac but could probably put my hands on one for the testing. That probably would work too. I do love the light bulb instead of the main fuse but that is not going to work here at all, I am pretty sure. Oh, and use a small fuse, yes yes, that would be correct. Just bridge out the T1 and T2 terminals on that triac in the AC supply. The PSU then reverts to entirely conventional - but will produce full DC rails with only 65% of nominal AC volts going in. Go any higher and the tranny's magnetic core will saturate and blow the AC fuse. Use a small fuse ( ie 1 or 2 amps) when playing about. It seems to be a matter of replace the for sure bad ****, check all around, pray, keep fingers crossed, plug it in and watch for smoke. :( I am pretty sure I found the bad ****, 2 GMA4A fuses, 1 2SA1302 and 1 2SC3181major output transistors (The big flat plastic ones) and two of four IRF640 are shorted. Cannot find anything more than that bad. I think I will pass on the smoke and disaster, the idea you've pointed out just might work. Thanks! ** Recipe for disaster. ...... Phil Cheers, Phil. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
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Where and how do you find or get schematics?
"BobW" wrote in
: I have always been able to find schematics that I need by using a search engine. Here's one for you: www.google.com Bob Thank you Miss LaTella. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
Where and how do you find or get schematics?
"Ohmster" "Phil Allison" I am afraid to try to fire this thing up when fixed because of that Carver "magnetic field core" power supply, I cannot variac it up slow and watch the current nor can I use a 100 watt light bulb in place of the main fuse. ** Sure you can. The dickens you say. I attached a small piece of the Carver M-400 PSU or you can see it he http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif Using this diagram, you are saying to just "short the triac" with wire, main terminal to main terminal, leave the gate alone. For sure this would make WAY to much power and blow the thing up but you say to bring it up slow with a variac and stay down around 50-65% of the AC line and monitor the "rails" on the amp to see if it is stable, not dumping DC, and does not draw excessive current? Hey that is brillient! Dam, I don't have a variac but could probably put my hands on one for the testing. That probably would work too. ** Its the way I usually test all Carver " Mag Field" amps that have had internal repairs done. There is no regulation, so the DC rails sag badly when he amp is under drive and load. When all is OK - undo the link. I do love the light bulb instead of the main fuse but that is not going to work here at all, I am pretty sure. ** Use one if you like. Or just monitor the AC current draw with a 3.5 digit AC meter - preferably true rms type. ...... Phil |
Tim Williams = a pox on society
"Tim Williams Posturing ****head from the Sewer " "Ohmster" How and where do you guys find schematics that you need to get a job done? I write them... We call it design. ** Vile piles of sociopathic, autistic **** like Tim Williams are a pernicious social disease - leeches on the rest of society. Just like any human disease, 100% eradication is the only way to go. If you know Keith, or anyone vile puke like him. Murder him. Any way you like. ....... Phil |
Where and how do you find or get schematics?
"Ohmster" wrote in message
... How and where do you guys find schematics that you need to get a job done? I write them... We call it design. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms |
Where and how do you find or get schematics?
In article ,
Ohmster wrote: How and where do you guys find schematics that you need to get a job done? .... So do you make a polite request in a Usenet newsgroup (Which one(s)? Despite the conversations here, a.b.s.electronics is just an auxillary group set up to support the other electronics newsgroups because they aren't supposed to have binary postings (and they get filtered out at many sites if they do), Start in sci.electronics.repair and put the name and model number in the Subject: line. Mark Zenier Googleproofaddress(account:mzenier provider:eskimo domain:com) |
Where and how do you find or get schematics?
"Tim Williams" wrote in news:iYkVi.11$v%4.7
@newsfe05.lga: "Ohmster" wrote in message ... How and where do you guys find schematics that you need to get a job done? I write them... We call it design. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms Yeah that is real sweet if you can do that but I am afraid it does not help me much. Good day. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
Where and how do you find or get schematics?
"Phil Allison" wrote in
: Hey thanks for writing back Phil. You may not have a schematic but at least you have experience with these particular kinds of amplifiers and are willing to help out a fellow tech and that goes a long way by itself. Thank you my friend. Having a friend with experience is sometimes better than even having the schematic. (I did write to Sunfire tech and asked for a pdf of the schematic but got no answer so far.) I the bad parts I found we Quantity Part Number Description 1 2SA1302 Audio Output Transistor 1 2SC3181 Audio Output Transistor 2 IRF640 MOSFET Power Device 2 GMA 4A 250V GMA Size Fuse All of these were on the amp board and I did not find any other for sure bad parts. The trouble I am having is finding this triac. This is a Sunfire, "True Subwoofer Super Junior" (Hell of a model number, huh?) and when my friend Bob was measuring the DC on the two main caps, he was telling me there was like 157 VDC on each of them. Impossible I say, only Carver does stuff like that and then he showed me, silk screened on the small power board "Designed By Bob Carver". "Ohhhhh", I said, it must be one of those mag field amps. I am probably going to have to put up some pictures of the amp and boards for you to look at Phil because I really cannot find this triac and am not sure where to look. This is a weird subwoofer for sure. The whole thing is a 9" cube, has an 8" passive on one side, and an 8" driver on the other side of the cube with double magnets that are so strong that if you put screws in a strong plastic bag into the unit and then pull the bag out, the screws will stay stuck on the speaker magnet and the bag will rip. Pushing in the driver by hand is very tough, this is no "breath easy" driver, that is for sure, this thing NEEDS tons of power to push the driver. The dickens you say. I attached a small piece of the Carver M-400 PSU or you can see it he http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif Using this diagram, you are saying to just "short the triac" with wire, main terminal to main terminal, leave the gate alone. For sure this would make WAY to much power and blow the thing up but you say to bring it up slow with a variac and stay down around 50-65% of the AC line and monitor the "rails" on the amp to see if it is stable, not dumping DC, and does not draw excessive current? Hey that is brilliant! Dam, I don't have a variac but could probably put my hands on one for the testing. That probably would work too. ** Its the way I usually test all Carver " Mag Field" amps that have had internal repairs done. Well, finding this triac is getting to be a trying experience so far. It would have to be a fairly good sized part, yes? At least a TO220 case or larger. i Don't see anything like that on the power board but for an L7812CV and an L7912CV which are just + & - 12 volt regulators and there is a very small transformer on the power board. The house AC also goes straight to two very large diodes (After being cleaned by a choke) and then to the two 1,000uF 200V capacitors. Ugh, I just broke down and called up Sunfire Tech and spoke to Shad. He took my name and number and said that all Sunfire amps are fixed at the factory. There are no service manuals or schematics available to anyone in order to protect their intellectual property. This unit does not use a triac and he had a name for it but I forget what it was. He was a decent guy but could not release too much information about the amp. He said there is a woman there that knows Bob Carver and she has been there for decades and does ALL of the Sunfire amps so Shad did not know all of the technical information about the amp in great detail. I told him about the two main outputs blown and the two MOSFETS blown and said I did not find anything else wrong and is it possible that this could be all that is wrong with the amp? Again he was not sure, the woman who fixes them and all that. He gave me the standard "Flat rate to fix the product is $275, ship it right off to us and we will get it done for you, etc.". I told him I went this far and had to at least give it a try. He understood and has me logged in case I want to send it in for repair. So, there is no triac in this product, there is 151 VDC across each main cap, there is 302 VDC across both main caps at the same time as measured with a Fluke, and Sunfire will release no technical information about the product for fear of losing "intellectual property". Ugh. There is no regulation, so the DC rails sag badly when he amp is under drive and load. When all is OK - undo the link. I do love the light bulb instead of the main fuse but that is not going to work here at all, I am pretty sure. ** Use one if you like. I probably will do this although I doubt it will save the amp or anything if something is wrong. I don't think I can use a variac but will try it anyway to see what happens. Or just monitor the AC current draw with a 3.5 digit AC meter - preferably true rms type. ..... Phil Man, I was going to snap you a picture or two of the 9" cube cabinet showing the two drivers (One passive) with my desk cam and when I got the cube within 3 feet of the monitor, the entire monitor discolored so badly from the super strong magnetic field of the driver magnets that I had to take it away from the computer. Anyway, here is what I have in the way of pictures of the boards: http://www.ohmster.com/~ohmster/sunfire/ Anyway, this is what the product looks like: http://www.sunfire.com/SuperJrPR.htm I really don't know what to do about this now Phil, what would you suggest? Check and check again for anything that is shorted or open, visually inspect, and if all looks okay, replace the two IRF640 MOSFETS (These are common MOSFET output devices in the Pioneer Elite receivers.) and the two shorted output transistors, 2SA1302 & 2SC3181 and then what, just plug it in and keep fingers crossed? Do you think it is worth trying to use a variac or light bulb in place of the fuse? This is a strange one, what do you think, Phil? I need your input. Thanks buddy. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
Tim Williams = a pox on society
"Phil Allison" wrote in message ... "Tim Williams Posturing ****head from the Sewer " "Ohmster" How and where do you guys find schematics that you need to get a job done? I write them... We call it design. ** Vile piles of sociopathic, autistic **** like Tim Williams are a pernicious social disease - leeches on the rest of society. Just like any human disease, 100% eradication is the only way to go. If you know Keith, or anyone vile puke like him. Murder him. Any way you like. ...... Phil Skipped your meds again?! |
Where and how do you find or get schematics?
"Ohmster" This is a strange one, what do you think, Phil? I need your input. Thanks buddy. ** Looks like that amp uses a SMPS ( switch mode power supply). The whole thing is quite bizarre. A powered sub woofer in a 9 inch cube - strewth !! Let Sunfire do it, they have built that thing so it is fit for factory service only. ........ Phil |
Where and how do you find or get schematics?
"Phil Allison" wrote in
: This is a strange one, what do you think, Phil? I need your input. Thanks buddy. ** Looks like that amp uses a SMPS ( switch mode power supply). The whole thing is quite bizarre. A powered sub woofer in a 9 inch cube - strewth !! Let Sunfire do it, they have built that thing so it is fit for factory service only. ....... Phil I will tell you what, the magnets in the driver has got to be the strongest magnet I have ever seen, dude. It is so hard to press the diaphragm in with your fingers that it would take massive force just to move it. I put screws for the unit in a very strong freezer zip lock back and when I pull the bag of screws out, the screws stay stuck to the magnet, the bag rips, and I end up with an empty, ripped freezer zip lock bag. When I put the 9" cube with the driver in it near my computer to take a deskcam picture for you, my monitor turns green and purple when the darned cube is over 3 feet away! Not just a little green and purple, but the whole image is massively discolored because of the strength of the magnets used in this speaker. Bob Carver did publish a white paper on his super subwoofers here if you are bored and want to read a bit about just how this stuff is supposed to work: http://www.sunfire.com/pdf/Sunfire_S...Whitepaper.pdf No, it is not an smps, they had a word for it but I forgot what the hell they called it, oh yeah, the power supply circuit utilized in this amp to make tons of power but only supply what the amp needs at the time is called "A Tracking Downconverter Circuit". To me is sounds pretty much like the same **** with the triac but they found a new way of doing it. I did use my meter and found that the two big caps. 1,000uF @ 200V are in series and go down to the amp board. There is no "transformer to speak of other than a small one on the small power board. The big caps get line voltage, rectified directly to them and might even use a voltage doubler configuration to end up with the 302 VDC that I observed across both caps. Full wave rectification on 120 VAC house current yields about 160 VDC or so. The small transformer has small diodes with +12 and -12 volt regulators on the board. Small standby current to run the low level and turn on circuits, no doubt. It looks like the common connection between the two big caps is speaker ground. I think that the IRF640 MOSFETS (Datasheets here): http://www.alldatasheet.com/view.jsp?Searchword=IRF640 Are part of this Tracking Downconverter Circuit and when the two large output bipolar transistors blew, 2SA1302 & 2SC3181, they took out two of the MOSFETS with them. This is all speculation as I have no schematic because Bob Carver wants to keep that circuit as intellectual property. So the 6 parts I need; 2 GMA4A fuses, 2 IRF640 MOSFETS, and 2 bipolar output transistors cost maybe $25 or less, I will recheck for anything shorted, open, or burned, then put them in and hope for the best. If it works, great. If it smokes, then I lose the job and it goes back to Sunfire for repair at the flat rate of $275. Any last minute tips, Phil? Just plug it in and keep fingers crossed? Try the light bulb or variac? What do you think? Thanks for sticking with me on this Phil, because I really had no idea of how to proceed or what to do about this situation and even just talking to another knowledgeable person is enough to help one make up one's mind. -- ~Ohmster | ohmster /a/t/ ohmster dot com Put "messageforohmster" in message body (That is Message Body, not Subject!) to pass my spam filter. |
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